This research project represents the first attempt to determine each of the relevant electrical stimulus parameters--current, voltage, and electrode-tissue interface resistance--necessary to elicit erection and ejaculation in the human male. The expertise of several disciplines: reproductive medicine, sexual therapy, physiology, and biomedical engineering--are being combined with the goal of developing rectal probe electrostimulation (RPE) as a practical method for obtaining erection and/or ejaculation in patients, who, for a variety of reasons, are unable to accomplish these activities themselves despite apparent normal gonadal function. Initially, we are using healthy male medical student volunteers to determine the normal baseline parameters. Then, we will apply these techniques and data to patients, especially those with spinal cord injuries or with impotence arising from physiologic causes. Hopefully, in the situation of married couples in which the male partner is having difficulty with erection and/or ejaculation, this study will provide a means for maintaining the sexual component of the marital unit and allow the fostering of progeny if desired. RPE may also be developed as a diagnostic tool in the study of neuropathy affecting the urogenital system, and in distinguishing between physiologic and psychologic impotence.